Linux Create Software RAID 1 (Mirror) Array

1. install md module

yum install mdadm

2. clean supber block

mdadm --zero-superblock /dev/sdc /dev/sdd

3. create raid 1 

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdc1 /dev/sdd1

4. now you can mkfs or use block dev derectly.

5. get raid info from md device

mdadm --query /dev/md0